Manufacture of azoxy-arylamines



. pounds containing free Patented Sept. 17, 1935 UNHTMD FFHQE 2,014,522 MANUFACTURE OF AZOXY-ARYLAMINES Miles A. Dal len and James I. Carr, Wilmington,

DeL, assignors C mp n Delaware to E. l. du Pont de l lemours & Wilmingtom'DeL, a corporation of No Drawing. Application April 10, 1934.

Serial No.

7 Claims.

This invention relates to organic compounds useful in ye Mor pa icul ly, it proved method for arylamines by the reduction of nitroarylamines f t neral ormu a:

wherein R, is an aryl radical or" the benzene or naphthalene series, The products of this reduction may be represented by the general formula:

the manufacture of the manufacture of relates to an im- Formula I is the one generally found in patent literature; recently, however, Formula II has been proven as more probable. (Tse-Tsing Chu and Marvel, J. Am. Chem. 500., vol. 55, pages It is to be understood that my invention is not conditioned upon or limited by the correctness of either formula.

The reduction of nitro-aryl compounds to the corresponding azoxy bodies has effected in the art by the aid of zinc dust in the alkali. This process is ap- However, this method is not applicable to the reduction of nitro-aryl comamino groups, and if, applied to these compounds, produces various tarry lay-products.

It is accordingly an object of this invention to provide a process for the reduction of nitroarylgenerally been the reducing agent. We have found that when this reducing agent is employed, the nitro-aryl- S amine is reduced successfully to the corresponding azoxy-arylaniine, Without the production of undesirable by-products to any appreciable extent; and the product so obtained is characterized by a high degree of purity.

The reduction is preferably eiiected in aqueous medium. and {for best results, the other conditions of the reaction, such as temperature, agita- These .9 optimum limits, however, are easily determined for each individual nitro-arylamine, and there is no danger of over-reduction even if one deviates slightly from these limits.

Example 30 In a suitable vessel equipped with a reflux condenser, 138 parts of meta-nitraniline, parts of caustic soda and 580 parts of Water are stirred together and heated to boiling. A solution of 35 it may be recrystallized from an organic solvent, such as alcohol or toluene. The yield is of the theory or higher, based on the weight of the meta nitraniline used.

In a similar manner the azoxy derivatives from other nitroarylamines may be prepared. The following table lists a number of typical nitroarylamines which may be reduced by the same general method, together with the azoxy-arylamines obtainable from each:

2,2'-diamino-azoxybenzene 4A-diumino-azoxybenzene 3,3 diamino 4,4 dimethyb azoxybenzene Ortho-nitrnniline Para-n itraniline 4-N1tro-2-aminc-toluene- 5-Nitro-2-ainino-toluene 3,3 dimethyl 4, 4--diamin0- azoxybenzene 3-Nitro-4-amino-toluene 2,2 diamino 5,5- dime thylazoxybenzene 4-Cliloro-2nitranilino u 2 2 diamino 5,5 dichloroazoxybenzcno 2-Br0mo l-nitraniline 4 ,4 diamino 3, 3'-dibromouzoxybenzene l-Nitro-2-amino anisole 3,3- diamino-4,4-dimethoxyazoxybenzene 3-Nitro-4-amino-anisole 2,2-(liamino -5,5'-dimetl1oxyazoxybenzene 4-Nitro-2-amino-diphenyletlior- 3,3-diamino-4,4-diphenoxyazoxybenzene 3-Nitro--l-amino-azobenzene 2, 2 diamino 5,5 diphenyl azo-azoxybenzene 4-Nitro-1-naphthylamino 4% (ii-amino.- uzoxynaphthaene l-Nitro-ZZ-nuplithylainine 2.?i diamino azoxynaphthaene 3-Nitro-4-amino-diplienyL 2,2 (liamino 5,5 1 diphenylazoxybenzene As already mentioned, the particular conditions of operation may be varied in each instance within the skill of the chemist, to suit the particular properties or behaviour of the arylamine being reduced. Thus, although the reduction process may usually be carried out in aqueous solution or suspension, in the instances where the nitroarylamine and/or the azoxy-arylamine are high in melting-point, low in solubility, etc., it may be desirable to add varying quantities of organic solvents, such as methanol, ethyl alcohol, ethyleneglycol, toluene, solvent naphtha, chlorobenzene, etc., to the reaction mass to facilitate attack of the nitro group by the reducing agent.

Instead of sodium arsenite, other arsenites, particularly that of potassium, calcium or ammonium, may be used. Arsenious acid or arsenious oxide with a solution of the corresponding metal hydroxide, may also be used.

The temperatures involved in the reaction may be varied within wide limits.

Many other variations and modifications are possible in our preferred mode of procedure without departing from the spirit of this invention.

We claim:

1. The process of producing an azoxy-arylamine of the benzene or naphthalene series, which comprises reducing the corresponding nitroarylamine by the aid of a metal arsenite in alkaline medium.

2. The process of producing an azoxy-arylamine of the benzene series, which comprises reducing the corresponding nitro-arylamine of the benzene series by the aid of an arsenite in alkaline medium.

3. The process of producing an azoxyarylamine of the benzene series, which comprises reducing a metanitroaniline compound by the aid of an alkali-metal arsenite in aqueous alkaline medium.

4. The process of producing 3,3-diaminoazoxybenzene, which comprises reducing metanitraniline by the aid of an alkali-metal arsenite in aqueous alkaline medium.

5. The process of producing 3,3-diaminoazoxybenzene, which comprises reducing metanitraniline in boiling aqueous alkaline medium, by the aid of an arsenite selected from the group consisting of sodium, potassium, ammonium, and calcium arsenites.

6. The azoxybenzene, which comprises reacting upon substantially 138 parts of metanitraniline, suspended in substantially 500 parts of water containing parts of caustic soda, at the boiling point of the mixture, with an arsenite solution obtained from substantially 185 parts of arsenious oxide, parts of caustic soda and 600 parts of water.

'7. The process of producing 3,3diaminoazoxybenzene, which comprises reacting upon substantially 138 parts of metanitraniline, suspended in substantially 500 parts of water containing 100 parts of caustic soda, at the boiling point of the mixture,with an arsenite solution obtained from substantially parts of arsenious oxide, 125 parts of caustic soda and 600 parts of water, and continuing the heating for a period of substantially 8 hours.

MILES A. DAI-lLEN. JAMES I. CARR.

process of producing 3,3-diamino- 

